Remove the husks from the tomatillos, and rinse under warm water to remove the sticky coating. Trim off the tops, and place on a foil lined baking sheet.
Add the whole serrano peppers and the garlic cloves in their skins to the baking sheet.
Broil for about 10 minutes, until the skins on the tomatillos start to blacken. Stay near the oven, as all ovens are different, and you don't want to burn anything.
Allow the vegetables to cool on the pan.
Using gloves, remove the stem and seeds from the peppers. Remove the skins from the garlic as well.
Place all the roasted vegetables along with the peeled shallot, fresh cilantro leaves, lime juice, and salt in a food processor. Process on high until relatively smooth.
Add more salt or lime juice if needed.
Enjoy with chips or on tacos or burritos!
Notes
Store leftover salsa in the refrigerator for up to five days.